Quote Originally Posted by ChristopherCoy View Post
I am asking because It took me 3 5x7 sheets, and 3 8x10 sheets to get this one 8x10 right. I want to try and have an idea of how the distance may change my exposure time, before I start wasting 16x20 sheets...
Some calcualtions will get you in the ballpark, but there are other things besides inverse square that matter too, so it's always best to do a test print.

Just go ahead and project, seek out some portion of the projected image that contains the tones you want, and do a test on a small fragment of paper. There is seldom a need to test the entire image.

When I get a new box of paper, I often sacrifice one sheet to make some test pieces for this kind of thing. The test pieces get exposed developed, topped, fixed, washed, dried... before I draw any conclusions about exposure of the "real" prints.

You shouldn't have to waste hardly any paper at all- test strips can tell you almost everything you need.... before you do the real thing.